Suspending the axle above the leaf makes the job way easier. Start by pulling the old leaf spring. Put the short side of the new Skyjacker leaf spring in the frame mount and run the bolt through, but don't tighten it yet. Attach the shackle side and drop the axle into place on the leaf spring. Do one side at a time so the axle is always supported by one leaf spring. Make sure the center pins go into the proper holes on the spring perches.